Process for separating wax from wax-containing oils



Patented July 23, 1940 PATENT OFFICE PROCESS FOR SEPARATING WAX FROM WAX-CONTAINING OILS Walter W. N. Meyer, Berlin, Germany, assignor to Standard Oil Development Company, a corporation of Delaware N Drawing. Application May 18, 1938,

Serial No. 208,601

9 Claims.

The present invention relates to an improved method for separating waxy constituents from wax-bearing oils in order to produce dewaxed oils of low cold test. The invention particularly relates to the production of mineral oils of low cold test from petroleum oils which contain appreciable amounts of waxy hydrocarbons and is concerned more specifically with an improved method for removing amorphous Waxy hydrocarbons from petroleum oils containing the same. The improved process of the present invention is obtained by utilizing in a dewaxing operation relatively inexpensive substances of the class of wool fat, W001 grease or degras, cholesterol, lanolin and the like as wax modifying agents or dewaxing, filtering or wax separation aids.

It is well known in the art to separate the waxy constituents from wax-bearing mineral oils by various methods, all of which have in common the feature of solidifying the solid wax by cooling or chilling the oil to relatively low temperatures. The separation of the solid precipitated wax from the oil is then effected, for example, by allowing the precipitated waxto settle by gravity or by centrifuging or by filtering the oil either in the usual plate or frame presses or by means of centrifugal filters. It is also well known in the art to facilitate and accelerate the separation of the wax from the wax-bearing mineral oil by adding materials such as diluents and the so-called settling and filtering aids.

In the usual processes the oil is preferably diluted with various solvents as, for example,

naphtha, octane, heptane, hexane, pentane, liquid butane and propane or other liquefied normally gaseous hydrocarbons either alone or in various combinations with each other. However, in dewaxing processes in which only a diluent was used, it was necessary to gradually cool the 40 mixture over a period as high as several days since too rapid cooling of the liquid mixture caused. the entire body to congeal into a semi-solid or pasty mass which could not be subsequently separated. This difficulty was overcome to some extent by 45 the use of a small quantity of oil soluble substance known as separation aids which apparently modified the wax crystalline structure so that considerably greater cooling and filtering rates could be employed. These separation aids or 50 wax modifiers wereof varioustypes and structures and were produced by a great many different methods. For example, asphaltic materials produced by high temperature oxidation of petroleum products have been used as well 'as' asphaltic materials which are secured from heavy 5 petroleum residues by precipitation with a known class of solvents which are miscible with theoil and precipitate the asphalts. Asphaltic materials obtained as residues in the distillation of asphaltic base oils are also satisfactory, as well as sub-' stances of the class of materials derived from paraffin wax.

The substances with which .the present inven-. tion is concerned are of an entirely different type. and structure and have not heretofore been used in dewaxing or dewaxing operations or similar processes. The substances of the present invention are of the class of wool fat, wool grease or degras, cholesterol and lanolin. Constituentsof wool fat or wool grease as, for example, wool fat alcohols, wool fat stearine and wool fat ethe rs may be used also, as well as particular fractions of these substances which may be separated by, known means as, for example, by distillation processes or by solvent treating processes.

These materials may be secured in any manner whatsoever and may be refined to any extent desirable. It may be preferable to use a particular constituent of the wool fat as, for example, cholesterol or to use a higher boiling fraction of the wool fat which is segregated by distillation or by means of selective solvents. V

The separation aids of the present invention may be utilized in any concentration desirable. It is, however, preferred to add these materials in a concentration from 0.1 to 5.0%, preferably in the concentration from 0.5 to 2.0%.

It has been found that these materials greatly accelerate the separation'of the waxy constituents from wax bearing petroleum oils. When 40 substances of the present invention are employed, the rate of cooling can be greatly increased with out solidification or gellification and the rate of settling of the waxy constituents is also greatly accelerated giving a clear separation. The substances of the present invention also aid in se'paf ration of the waxy constituents by centrifuging or by filtering. I p 7 These substances may be employed in dewaxing operations in which any particular type of dilujiso ent or solvent is employed. However, particularly desirable solvents are naphtha or solvents of the type which are heavier than the solid waxes themselves. Among the solvents included in this class are halogenated aliphatic or aromatic hydrocarbons such as carbon tetrachloride, dichlorethane, difluorpropane, tribromethane, dichlorethylene, trichlorpropylene, chlorbenzol or toluol and the like. While these solvents may be used alone it is preferred to use them in combinations, either with each other orsome other materials such as benzol, toluol, xylol and petroleum naphthas, ranging from propane to octane and heavier. The solvent is preferably selected so as to have a freezing point considerably below the temperature at which the wax separation is eifective, also to have as low a solvent power for waxes at the separation temperature as possible, which makes for the least possible spread between wax separation temperature and the pour point of the oil produced. Particularly useful combinations of these types of solvents are as follows:

Dichlorethane 75 Carbon tetrachloride 25 Dichlorpropane 70 Carbon tetrachloride 30 Dichlorethane Q 50 Dichlorethylene 50 Dilchlorethane 60 Trifluorethylene 40 Dichlorethane 70 Carbon tetrachloride; 20 Trichlorethylene Dichlor ethane 70 Benzol l 30 Dichlorpropane 75 Toluol Xylol 10 Ethylene difluoride 70 Carbon tetrachloride 15 Naphtha 15 It should also be preferred to select such a combination of solvents, as those above, which do not tend to separate the oil into mutually insoluble layers, at or near the temperature of wax separation, and in whichtheseparation aid is barely soluble. The composition of the solvent can be readily varied so as tobring about this condi-.

tion and to produce a slight turbidity. When the solvent dissolves the aid completely forming a clear solution, the separation aid is almost always of low activity.

These solvents or diluents may be present in any desired concentration. depending upon the particular solvent being used, the grade of oil being treated, the waxy constituents present, the grade of dewaxed oil desired, as well as upon the temperature of treatment. In general, these solvents or diluents are preferably present in the concentration of from 1 to 4 volumes of solvent per one volume of oil being treated.

Other conditions of the 'dewaxing process such as pressure, temperature, rate of cooling, settling time, filtering rates and mode of separation of the waxy constituents may be optimumly adjusted Per cent and depend to a large extent upon the oil being dewaxed, the concentration of the waxy constituents present, the grade of dewaxed oil desired and upon the particular solvent being used. Dewaxed oil suitable for certain purposes may be secured by chilling to a temperature of from 5 to 10 F., although a particularly desirable oil is secured by chilling to a temperature of from to F. or lower. The rate of chilling may be 25 to F. per hour or higher.

The invention may bemore readily understood by reference to the following examples given for the purpose of illustration and are not to be construed as limiting the invention in any manner whatsoever.

Example 1 A series of blends were made using a commercial separation aid and a separation aid of the present invention in an untreated Panhandle .distillate having a viscosity of 62 seconds Saybolt at 210 F., which distillate represented about a 6% cut on the crude. Approximately 3 volumes of naphtha diluent were used per volume of Panhandle distillate and the respective blends were rapidly chilled to 44 F. The results of these W001 fats were secured from 9 diflerent sources and were tested on an untreated Panhandle distillate having a viscosity of 67 seconds Saybolt at 210 F. In these tests approximately 3 volumes of naphtha were used per volume of distillate and the mixtures rapidly chilled to 36 F. The results of these tests were as follows:

Percent Percent Bath temp.

Test clear 0' mhlbltor solution F.

None Solid 36 1 48 36 1 65 -36 1 49 36 1 36 l -32 1 60 36 1 52 +36 1 v 45, 30 1 72 30 Example 3 78 parts by weight of wool fat were dissolved in about 740 parts by weight of fiuxing naphtha and the mixture was rapidly chilled to 34 E. This mixture was then separated into 61% precipitate and 39% filtrate. These fractions were then tested as filtering aids in a Panhandle distillate having a viscosity of 50 secondsqsaybolt at 210 F. Approximately 3 volumes of naphtha were used per volume of distillateand the respective mixtures were chilled rapidly to 36 F. The results of these tests were as follows:

Percent Percent Test Kmd i aid of clear Remarks inhibitor solution 1 Original wool fat 0. 5 Solid.

do 1.0 35 0.5 55 1.0 60 0.5 0 Solid. o 1.0 0 Do. 7 Blend of precipitate 0.5 0 Very viscous.

and filtrate. 8 do 1.0 40

Example 4 W001 fat was distilled under vacuum conditions and 56% was taken overhead in five 10% cuts and one 6% cut, the final still temperature being 650 F. and a pressure of 0.1 inch mercury. Cold settling tests were then run over a period of ten hours using a Panhandle distillate having a viscosity of 50 seconds Saybolt at 210 F. described in the preceding example using 3 volumes of naphtha per volume of oil with the following results:

Example W001 fat was distilled in the manner described in Example 4 and the distillation was carried to 77% bottoms and a final still temperature of 590 F. at a pressure of 0.1 inch mercury. Settling aid tests were then run on these fractions in the manner described in Example 4 with the following results:

Percent settling Bath Percent Test Settling aid used aidbased temp., clear marks on waxy F. solution oil 77% bottoms 0. 5 35 15 .do .1 1.0 35 55 23% overhead 1.0 35 0 Solid.

Blend of 23% over- 1.0 35 46 head and 77% bottoms.

Example 6' A sample of a lube plant charge stock was blended with 1% of wool fat and fluxed with 3 volumes of naphtha per volume of said stock. This material was then chilled rapidly and the material dewaxed by filtering. The dewaxed stock was then treated with 25 lbs. of 98% sulfuric acid per barrel and contacted with 1 lb. per gallon of Gonzalas clay for two hours at 350 F. Inspections were then run on the filtered dewaxed oil and the results were as follows:

Gravity A. P. I 26.3 Flash, F 495 Fire, "F 575 Viscosity Saybolt at 100 F 736 Viscosity Saybolt at 210 F 72.4 Viscosity index 8'1 Carbon, per cent .44 Robinson color, original 9 A 16 hrs. at 250 F 6% 16 hrs. at 250 F. of oil of average stability 5% Steam emulsion number 145 Neutralization value 0.07

From the above data it may be readily seen that the separation aid of the present invention had no adverse effects on the quality of the dewaxed lubricating oil.

The above invention is not to be limited by any theory or mode of operation, but only by the following claims in which it is desired to claim all novelty insofar as the prior art permits.

I claim:

1. A process for conditioning oils preparatory to the separation of wax therefrom which comprises mixing said wax and oil with a wax separation aid containing cholesterol.

2. A process for separating wax from wax-oil mixtures which comprises mixing the wax-oil mixture with a wax separation aid containing cholesterol, chilling the mixture to solidify the wax content and separating the solidified wax from the oil.

3. A process for separating wax from wax-oil mixtures which comprises mixing the wax-oil mixture with a wax separationaid containing cholesterol and a diluent, chilling the mixture to solidify the wax content and separating the solidified wax from the oil.

4. A process as in claim 2 in which the wax separation aid comprises wool grease.

5. A process as in claim 2 in which the wax separation aid comprises lanolin.

6. A process as in claim 3 in which the wax separation aid comprises wool grease. I

7. A process as in claim 3 in which the wax separation aid comprises lanolin.

8. A process for conditioning oils preparatory to the separation of wax therefrom which comprises mixing said wax and oil with a wax separation aid secured by dissolving wool fat in a fiuxing medium, cooling the mixture rapidly, separating the precipitate and using the same as said wax separation aid.

9. A process for conditioning oils preparatory to the separation of wax therefrom which comprises mixing said wax and oil with a wax separation aid secured by distilling wool fat, segregating the bottoms and using the same as said Wax separation aid.

WALTER. W. N. MEYER. 

